final

• Variables can be final: cant change the value once you have initialised them.
• Methods can also be final, so you cant change their implementation in a subclass.
• Classes can be final: cant subclass them

Reviewing out classes so far

User interface Classes

• Every class is derived from object
• As we work down the class hierarchy, get more specialised

Containers have components

• A container can contain components
• A container IS-A component and can containers containers

Layout managers

• Containers have layout managers associated with them
• Can set the layout manager to use what layout
• A FlowLayout IS-A layout manager so a container can use it

Patterns

Strategy Pattern

Delegates some work to another class

• Get situations where a class has a number of responsibilities and it can implement each in multiple different ways
• Decide on the set of responsibilities and create an interface for them
• Can create different sub-classes which implement the responsibilities differently
• Main object asks the implementer of interface to do the action whenever it is needed, rather than doing it itself

Observer Pattern

Notifying an object (or multiple objects) of a different class that an even has occurred

Java listeners

• Can notify an object of something by calling a method on it
• Caller knows that listener IS-AN ActionListener, so it knows it can call its actionPerformcd() method to tell it when something happens
• Caller does not know what the listener will do in reaction to being told
• Listener could also support other interfaces

Nested and Inner Classes

Can defined classes inside classes. Cant make the classes:

• static: not associated with object of outer class or not

Using Inner Classes

Classes inside another class Adaptors - Exist for many of the interfaces. These are classes which have empty implementations of the methods, so would only need to implement one